Aerofoil construction



Aug. 11, 1931. 1.. s. YOUNG AEROFOIL CONSTRUCTION Filed June 21. 1929 sSheets-Sheet 1 v ewm: Lena/5 6.1%:

Aug. 11, 1931. YQUNG 1,818,520

AEROFOIL CONSTRUCTION Filed June 21, 1929 3 Sheets-Sheet 2 v Swim/Mm: Lm 6. 101019, 55 M 6N0 MW W 'Aug. 11, 1931. L. e. YOUNG 1,818,520

- AEROFOIL CONSTRUCTION I Filed June 21, 1929 3 Sheets-Sheet 3 MM WPatented Aug. 11, 1931 PATENT. OFFICE,

LEWIS G. YOUNG, OF BRONXVILLE, NEW YORK AEROFOIL CONSTRUCTIONApplication filed .Tune 21,

This invention relates to the construction of aerofoils or aeroplanewings and is particularly concerned with the provision of a spar forinternally bracing a wing which is 1 curved along its span.

In-my copending application, SerialNo. 372,650 filed June 21, 1929,there is described a.wing spar which is curved along its span. Thepresent invention is concerned with a 19 modification of the spardescribed in said application. It is there proposed to construct a Wingwhich is laterally curved and which has a lifting surface relativelynear. the fuselage of the aeroplane, and which has 15 a stabilizingsurface extending laterally beyond the lifting surface and making adihedral angle therewith. The present spar is'especially adapted forinternally bracing such a wing. Thisspar in addition to being 29 lightin weight, simple to manufacture, and having a high factor of safety, isinternal of the wing and takes such form that the wingsurfaces coincidewith the upper and lower faces of the spar, the wing curves 2.5 being;determined by the spar.

The main feature of the invention thus resides in the provision of aspar for internally bracing a wing which has a dihedral angleintermediate its ends whereby the latm eral stability of theplane istremendously increased and, at the same time, a high factorwof safety ismaintained in the construction.

Other objects and advantages will.be apparent from the followingdetailed descrip tion of a'preferred embodiment of my invention inconnection with the accompanying drawings, wherein Figure 1 is a planView of a wing constructed according to the present invention.

Figure, 2 is a front elevation of the wing.

Figure 3 is a front view of the forward spar-shown in Figure 1.

Figures 4: to 10 inclusive, are cross sections of the wingtakenon thelines 44 to 1010'inclusive, in Figure 1, and looking in;the directionofthe arrow-s.

Figure-11 is a front view of a single wing spar extending on both'sidesof the fuselage.

f Figure-12 is a cross section of the wing 1929.. Serial N0. 372,651.

taken on the line 44 of Figure 1, and showing a modified form ofconstruction.

It will be understood that throughout the description the termlongitudinal refers tov a dimension fore and aft of the aeroplane,While: lateral means widthwise orv along the Wing span thereof.

In the embodiment of the invention illus trated each wing has asupporting surface adjacent to the fuselage andnear the leading edge ofthe wing, with a stabilizing surface longitudinallytothe rear. of thesupporting surface and, a" stabilizing surface laterally beyond the,lifting surface. The supporting surfacesare, so' curved andproportioned, that the pressure resultants of the two surfaces, whetherthe aeroplane be, inclined in one direction orv theother, tendtopreserve the, stability of the plane. hen the plane is banked, theresultant upward pressureagainst.the lower wing is increased while that.against the upper" wing is decreased and the plane is thus returnedto aposition of equilibrium. It has beenv found that it is desirable toconstruct the lifting surface with'a definite ratio of length. (latteraldimension) to chord, namely, two to one, although. other, ratios, suchas three to one are also possible. With a ratio of length to chordOftWOf to one, the, distances of the center ofv pressure of thelaterally stabilizingsurfaceand of the center of upward pressure, on theundersideof the wing from the longitudinal axis should also be in theratioof twoto one andthe distances of the center ofpressure of thelongitudinally stabilizing surface and of the center of upward pressureon the supporting surface from thelaterali axis should likewise be inthe ratio of two to one.

In cross section, the present wing has a forward portion which isconcave below. and a rearward portion with a reversely curvedlongitudinally extending stabilizing surface which meets the lowerforward surface. Laterally, the wing is also curved andhas a stabilizingsurface remote from the fuselage, the center of pressure of this surfacebeing at about twice the distance from the longitudinal axis of theplanev asis the center of the lifting surface. It will be understoodthat the two wings are symmetrical with respect to the longitudinal axisof the plane and a description of one will suffice for the other.

There is shown at w a wing constructed in accordance with the presentinvention. This wing consists, generally, of a lifting portion, beingthe part between the lines H and 88 of Figure 1, and a stabilizingportion being the part shown between 88 and the wing tip. This wing isconnected to the fuselage of the plane 4-4:, and is provided withsupporting spars a and a and with ribs 6. The leading edge of the wingis at 0 and the trailing edge at (Z, the usual supporting members 0 andd being provided adjacent the leading and trailing edges. The wing isshown as tapering, generally, to a point e at the wing tip. In the crosssectional views in Figures 4 to 10 inclusive, there is shown a wingtapering in thickness and having a particular surface as will bedescribed in detail below.

As the particular curvature of the wing along its span is of the utmostimportance, the exact positions of the wings with reference to a givenplane determined by the lines 8-8 in Figure 3 and ss in Figures 4 to 10is shown in great detail. It will be seen that the wing makes betweenits ends what may be termed a dihedral angle. That is, looking at thefront elevation of the wing, there is at first an upward curve. The wingthen curves downwardly to form a depressed portion between its ends andthen curves up slightly, preferably not reaching, however, a height asgreat as the first raised portion assumes. This is shown best in Figures4 to 10, wherein the reference lines ss' are horizontal and in a planepassing through the lower frontcorner of the spa-r a. 7

Since it is the particular construction of the spar which constitutesthe main feature of the present invention, the spar a is shown in detailin Figure 3. The spar a is similar in construction to the spar a andtakes positions relative to the latter as shown in Figures to 10.

The upper and lower wing surfaces are, of course, designed withgenerally. stream line form, but the lower surfaces have moreparticularly a concave portion mand a convex portion 11,, the formerbeing forward of the point is at which the curve reverses, and thelatter being to the rear of said point. It will be noted that the curvem is approximately twice the length of the curve 11, though thisproportion is not absolutely essential. However, when these curves arein a given ratio at one wing section, the ratio should be preserved atthe other wing sections. For convenience in descripition of the definiterelationship between the lifting portion of the wing and the stabilizingportion,

it may be noted that the lifting portion between lines 4.4: and 8-8 isof trapezoidal shape with long sides of approximately twice the lengthof its short sides. This approximate ratio of two to one between thelength and the width of the lifting section is the ratio whichdetermines the locations of the centers of pressure, whereby the planeis properly balanced. It will be understood, of course, that thisdefinite relationship is approximate only and is not absolute. The otherportion of the wing, from the line 88 to the wing tip comprises thestabilizing portion of thewing and has a leading edge which sweeps backto the wing tip which is approximately in line laterally with thetrailing edge of the wing at the fuselage.

In the copending case referred toabove the wing spars are shown straightlaterally. In the present invention the spars in addition to beingcurved to form dihedral anglesbetween their ends are also curved toextend so they lie further forward longitudinally at some points alongtheir spans than they do at others. The particular shapes illustrated inFigure 1 need notbe maintained, but in general the spars should beshaped to impart to the wing maximum strength, the leading sparcoinciding approximately with the centers of pressure along most of itslength.

Although the wing is shown as tapering in thickness from the fuselage tothe wing tip, a wing of constant thickness is also within the scope ofthis invention. It will also be apparent that the wings may form adihedral angle between them, or lie generally in the same plane, and mayhave sweep back or make any desired angle with the line of flight. SteelI-beam spars are shown in Figures 4: to 10 inclusive, but other metalsections or wood could be used instead. The particular type of rib usedforms no part of the present invention.

. In Figure 11, there is shown a single spar extending on both sides ofthe fuselage f and having sections a connecting the two sections a, eachof which latteris constructed according to the present invention.

In operation, it will be appreciated that should the plane start to noseover, the rear part of the wing, as shown in Figures 4 to 10 inclusive,will tend to rise relative to the forward portion and the smooth curveof the upper surface which meets the reverse curve of the lower surface,tends to produce a drag on the movement of the wing and to return theplane to normal flying position.

trailing edge tends to exert a force thereon which not only prevents theplane from taking an increased diving angle but actually restores thewings to a normal angle of attack.

Similarly, should the plane due to external forces acting thereon, tendto bank the resultant pressures on opposite sides of the fuselage willtend to right the plane because of the effect of the relative pressureson the sustaining or lifting surfaces, together with the oppositelyinclined stabilizing surfaces. The equilibrium of the plane thus tendsto be automatically restored whenever outside forces unbalance thestability of the plane.

The plane may be positively controlled by ailerons, rudder andelevators, not shown. Other details of the construction of the plane arenot shown as they do not form any part of the present invention.

Further, applicant does not wish to be limited to the specificembodiment shown, save as defined in the appended claims.

I claim as my invention:

1. In a wing, a spar which is curved toward and away from the leadingedge and which is formed with a dihedral angle between its ends andapproximately midway of the wing span and in the plane of the wing.

2. In an aeroplane having a wing formed with a dihedral angle betweenits ends, a plurality of spars formed in the wing and having dihedralangles between the ends thereof, the angle of the forward spar beingmore acute than that of the after spar.

This specification signed this 5th day of June A. D. 1929.

LEWIS G. YOUNG.

